Mueller obtained a new search warrant against Manafort last month, and it could signal a huge shift in the Russia investigation

The special counsel Robert Mueller obtained a search warrant against Paul Manafort, the former chairman of Donald Trump's 2016 presidential campaign, as recently as March 9, new court documents show.

The search warrant was related to "ongoing investigations that are not the subject of the current prosecutions involving Manafort," the documents say.

The revelation indicates Mueller's focus on Manafort is shifting from examining his lobbying work in Ukraine to whether he colluded with Russian officials while he was the Trump campaign chairman.

The special counsel Robert Mueller obtained a new search warrant against Paul Manafort, the former Trump campaign chairman, less than a month ago, according to court documents filed on Thursday.

The revelation is in an opposition filed by Mueller's office to Manafort's recent motion to compel the government to turn over unredacted versions of search and seizure warrants it had obtained against him.

The special counsel's office said that after Manafort raised the issue, the US government gave the defense copies of six affidavits — three of them had no redactions, and the other three had minimal redactions.

Per the court filing, the special counsel also obtained a new search warrant in the Manafort case on March 9. It turned over a redacted copy of it to the defense on Wednesday.

But Mueller's office also made another notable disclosure.

Four of the seven affidavits that had been produced for the defense were redacted because they contained information regarding "ongoing investigations that are not the subject of the current prosecutions involving Manafort," the filing says. The latest warrant has more "substantial redactions" than the other three.

Manafort has been charged with dozens of counts related to financial crimes and conspiracy against the US. The charges so far deal primarily with his lobbying work for pro-Russia interests in Ukraine and for Viktor Yanukovych, the former Ukrainian president.

Thursday's court filing indicates Mueller has found evidence of wrongdoing in the case that is not limited to Manafort's consulting work in Ukraine.

A recently released memo sent to Mueller from Deputy Attorney General Rod Rosenstein last year says the special counsel is authorized to investigate at least two threads as it relates to Manafort: allegations of criminal activity arising from his work in Ukraine, and allegations that he colluded with Russian officials as Russia was trying to meddle in the 2016 US election.

The rest of the Rosenstein memo was redacted, and legal experts have suggested it's possible Mueller was authorized to investigate additional allegations against Manafort outside of the collusion inquiry and his Ukraine lobbying.

The special counsel's office disclosed in Thursday's court filing a partial list of its warrants against Manafort. In addition to searching Manafort's home, bank accounts, email, and hard drive, prosecutors also secured permission to search "information associated with five telephone numbers controlled by AT&T," it said.

News that Mueller is broadening his focus in the Manafort inquiry is bolstered by recent reports that prosecutors told Manafort's longtime deputy Rick Gates they didn't need his cooperation against Manafort. Instead, they are said to be interested in learning more from him about the Trump campaign's contacts with Russians during the 2016 campaign.

Manafort and Gates are two of several Trump associates who are known to have been in touch with people linked to Russia during the campaign. The two men have known each other for at least three decades, and Gates was privy to most — if not all — of Manafort's dealings before the election.

Gates had what's known as a "queen for a day" interview with the special counsel in early February in which Gates answered questions from investigators, including those about his case and other possible criminal activity he may have seen.

Paul Manafort. AP Photo/Alex Brandon

Manafort has mounted an aggressive defense against the special counsel, saying the charges against him should be dropped because they do not deal with collusion with Russia. His lawyer has also argued that Mueller's mandate in the Russia investigation is "tantamount to a blank check."

The special counsel's office described Manafort's assertion that Mueller's mandate was too broad as "unsound."

It added that the Justice Department's regulations for the appointment of a special counsel gave Mueller "limited flexibility" while authorizing Rosenstein to amend the scope of Mueller's mandate where necessary "in order to fully investigate and resolve the matters assigned."

Mueller's office questioned Manafort's right to argue the validity of the special counsel's mandate at all, saying Manafort had "no basis" to use that reasoning to call for the dismissal of his case.

Specifically, Mueller's office said the DOJ regulations governing the appointment of a special counsel were meant to provide a framework for the department's internal structure. It said the regulations "unequivocally state" that they are not meant to "create any [enforceable] rights" in a criminal proceeding.